In my rome campaign I just used anything and everything cuz I didn't know how to prepare an army
For my parthia campaign and sassanid campaign I just used horse archers
But
As my last and best campaign yet
I started using some decent army loadout
And instead of just ambushing or rushing
I'm using mixed columns
Like
This pic
3 line of spearmen(the alemani smpearmen or soooo goooodddd) with gaps between for shock troop respons and archer retreat
Axe men at both ends for heavy infantry respons
4 tight spearmen just in case
And 4 line of archers cuz of long range and good damage
1 line of heavy infantry in the tip to absorb the shock and damage
And a dog and a light cav just in case
And one(two in this pic) generals for chasing or flanking